I imported an Xperia 10 IV about a month after launch. It's a brilliant form factor, but I'm very sad that it doesn't look like sailfish will ever arrive for it.
Nevertheless, I'm glad I bought it - and like you say, the headphone jack gets used frequently enough that you'd miss it if it wasn't there.
Where did you import your Xperia from? I got myself pretty sold on getting one but totally forgot that Sony don't sell phones in Aus anymore. Such a shame. I really want an sd card slot & headphone jack.